@ maxo,
Just because somebody somewhere built an SS15 with XYZ woofer is not a reason for Jbell to put a stamp of approval on it. Jbell has made recommendations based on HIS testing and expirence, if you choose to stray from them just remember YMMV.

Been following your posts and I know your excited to make a move on something. SS15's generally are an excellent choice for a live band, but low synth stuff and dubstep is going to be a problem for them. Realistically a high pass filter that removes that sort of content is a requirement.

Epa ,
The Tham fold looks good, but so does the SS15 style fold, a scaled up Brian Steele POC#2 type fold design might also work .... Forsman also came up with a Tham style with an extra fold that looks pretty crafty ... The link to his discussion is Thorn F1 - a learning experiance with Tapped Horn

My designs so far have a straight taper, so of course any of these folding styles would have to be adjusted to get a straight taper (instead of a rapid expansion at the end of the line) and also the compression, line length and taper ratio would all have to worked into the fold design to get the output to match my sims as close as possible ... A scaled up POC#2 is the closest in most regards, the fact that his design is "stepped" may not hurt one bit and would actually simplify the construction a little...

I have updated my SS-18PS76 inputs, it now has a slightly longer path length but its still only 209 liters, and seems to require less inductance to get flat, in fact i think this one could be run with no series inductance added to the 18PS76 driver, which means less expense and decreased losses .... The bump at 50 would likely be knocked down and flattened by the DFD mod.... By the way, for uber power handling an 18sound 18LW2400 also looks awesome in this cabinet with a little added inductance, the 18TBX100 and 18TBW100 also look decent enough with additional series inductance added ...

The dimensions seen in the comment field are rough dimensions for a super simple single fold cabinet...